Zhenghai Wang

(1) Background: The spontaneous combustion of coal (SCC) not only consumes huge amounts of coal resources but also causes environmental degradation. Rare earth elements (REE) can be taken as an effective indicator to evaluate the environmental effects of SCC. Coal in the Rujigou Mine has been spontaneously combusting for hundreds of years. (2) Methods: The geochemical properties of REE and major elements in the soil of the Rujigou coal mine are methodically examined to reveal the environmental effects of SCC. (3) Results: Soil REE concentration in the Rujigou mine is 216.09 mg/kg, and there is an enrichment of light rare earth elements (LREE) and a depletion of heavy rare earth elements (HREE), LREE/HREE in Rujigou mine was 5.52. The spontaneous combustion of coal could change the vertical distribution of REE, which is conducive to the enrichment of LREE. According to the Eu anomaly and δCe/δEu, the source of material in this mine may be derived from the terrigenous clastic rock controlled by weak reduction. Aluminum and titanium have similar geochemical behavior to REE, especially LREE. The concentration of sulfur is negatively correlated with REE, especially HREE. Calcium, sodium, and magnesium all had a negative correlation with LREE. (4) Conclusions: The spontaneous combustion of coal can lead to the fractionation of light and heavy rare earth elements, resulting in the enrichment of LREE and depletion of HREE.

Ground deformation poses an imminent threat to urban development. This study uses the multiscale geographically weighted regression (MGWR) model to investigate the spatial heterogeneity in factors influencing ground deformation, thereby elucidating the drivers behind regional variations in ground deformation patterns. To gain insights into the characteristics of ground deformation in Zhuhai, China, and its spatial relationship with natural and anthropogenic features, we initially utilized the small baseline subset interferometric synthetic aperture radar (SBAS-InSAR) method to collect data on ground deformation and its distribution across the entire area. Concurrently, remote sensing imagery was used to identify the various mechanisms affecting ground deformation during the same period, including geotectonic conditions, geographic environment, and human activities. Subsequently, we used the MGWR model to quantitatively estimate the effects of these driving force factors on ground deformation in Zhuhai. Our findings reveal significant ground deformation in specific areas, including Baijiao Town (Doumen District), Hongqi Town (Jinwan District), the Gaolan Port Economic Zone, and the northern part of Hengqin Town, with peak deformation rates reaching 117 mm/y. Key drivers of ground deformation in Zhuhai include NDVI, groundwater extraction intensity, and soft soil thickness. The application of the MGWR model, with an R-sq value of 0.910, outperformed both the global regression model ordinary least squares (OLS), with an R-sq value of 0.722, and the local regression model geographically weighted regression (GWR), with an R-sq value of 0.770, in identifying driving forces. This study can provide valuable insights for government policies aimed at mitigating the disaster risks associated with urban ground deformation.

This paper describes the effect of mineral elements on dominant plants in the Shewushan lateritic gold deposit, China. For this purpose, 30 soil profile samples at different depths and 3 kinds of dominant plants including Populus canadensis (Populus X canadensis Moench), Cinnamomun camphora (Cinnamomum camphora (L.) Presl.) and Rhus chinensis (Rhus chinensis Mill.) were collected. The concentration of ore-forming elements including Au, Ag, Pb, Zn, Cu, As, Fe, and S were analyzed. Based on the investigation of two mine profiles, it can be found that Au, Pb, As, and Fe were mainly enriched in laterite layer and the brown clay layer at a depth of 5–11 m. Moreover, the biological accumulate coefficient (BAC) and the contrast coefficient (CM) were calculated to assess the sensitivity and concentrating ability of Populus canadensis and Cinnamomun camphora. To investigate the response of the two species to metal stress, the contents of chlorophyll, malondialdehyde (MDA), and activities of superoxide dismutase (SOD) and peroxidase (POD) were determined. The result showed that Populus canadensis and Cinnamomun camphora have a high tolerance to metal stress and that both of the two species can indicate the content of Au, As, Pb, and Co in topsoil.

Plants that have grown for many years in the special environmental conditions prevailing in mining areas are naturally screened and show strong capacity to adapt to their environment. The present study investigated the enrichment characteristics of U and other heavy metals (As, Cu, Pb, Mn, Mo, Zn, Cd, Co, and Ni) in the soil–plant system in Xiazhuang uranium mine. Four dominant plants (Castanopsis carlesii, Rhus chinensis, Liriodendron chinense, and Sapium discolor) and soil samples were collected from the mined areas, unmined areas, and background areas away from the ore field. U, As, Cu, Pb, Mn, Mo, Zn, Cd, Co, and Ni concentrations were analyzed by ICP-MS. The results demonstrate that (1) The highest concentrations of U (4.1–206.9 mg/kg) and Pb (43.3–126.0 mg/kg) with the geoaccumulation index (I_geo) greater than 1 show that they are the main soil pollutants in the research area. (2) The biological accumulation coefficient (L_BAC) values for Cd, Mn, and Cu are greater than zero in S. discolor, L. chinense, and C. carlesii and these three plants indicate that they can be used for remediation of the soil in the ore field. (3) R. chinensis inhibits the accumulation of heavy metals and shows sensitive pigment responses to the accumulation of U in the leaves. L. chinense has the strongest enrichment effect on heavy metals but exhibits weak biochemical responses under U stress. C. carlesii demonstrates strong adaptation to U and can maintain healthy pigment characteristics in case of high U enrichment. (4) S. discolor, L. chinense, C. carlesii and R. chinensis have strong tolerance to U toxicity and different biochemical responses.

Heavy-metal pollutants in the soil and surface water of agricultural areas accumulate in rice and may have adverse effects on the health of consumers. In this study, we determined the levels of heavy-metal contamination in agricultural areas around the Xiazhuang uranium deposits in northern Guangdong Province, China, using equidistant sampling methods along a river near the mine tailings. The pH values of all the water samples were determined. The heavy-metal concentrations in water, bottom sludge, and rice were measured. The extent of contamination was evaluated by calculating Nemerow’s pollution index, contamination factor, and hazard quotient. The result shows U transferred from mine to soil and rice with irrigation water. The main pollutants and their pollution indices in soil are U (6.31), Th (4.02), Pb (2.52), Cd (2.36), Zn (1.52), and Mn (1.39). The rice grain can hardly enrich U and Th but were susceptible to Cr and Ni. The contamination factors (CFs) of the pollutants in rice grain are Cr (1.98) and Ni (3.09). The hazard quotient (HQ) shows that Cu (HQ > 1) could pose potential risks for humans upon long-term consumption of the rice.

The effects of high Cu, Pb, and Zn concentrations on pigments of Pinus massoniana L. ( PML ) growing near the Dabaoshan Pb-Zn polymetallic mine were evaluated. A total of 19 samples of PML needles and 15 samples of soil were collected near the mine and at a nearby background site to compare heavy metal (HM; Zn, Cu, Pb) accumulations. A 2D scatter plot was used to study the relationships between the pigments and each metal element. PML needles collected from the mining area had a significantly higher content of Pb (24.5 mg/kg) and Cu (26.1 mg/kg) than needles collected from the background site (Pb: 2.8 mg/kg, Cu: 6.7 mg/kg). The HM concentrations in the needles were positively correlated with the pigment contents (chlorophyll a, chlorophyll b and carotenoids) . This suggests that PML can adapt to HM stress and even promote growth within a certain range. In contrast, when the HM content in needles reached very high values (Cu: 50 mg/kg, Pb: 60 mg/kg, and Zn: 110 mg/kg), the normal physiological and biochemical functions were hindered. PML is highly resistant to HM pollution, making it a candidate for reforestation and restoration of Pb and other HMs in mine areas.